Acoustical mechanism



March 19, 1929. 4' M. M. GRUBER ACOUSTICAL MECHANISM Filed March 22, 1926 lNV NTOR liar/m I'I. r'uer ATTORNEY Patented Man 19, 1929.

UNITED STATES MORRIS M. GRUBER,

on NEW YORK, N. Y.

PATE

ACOUSTIGAL MECHANISM.

Application filed March 22, 1926. Serial No. 96,384.

My invention relates to acoiistical mechanisms of the type employing a vibratory diaphragm in connection with some other acoustical member such as a horn or a sound chamber for clarifying and amplifying the the sounds produced initially by the diaphragm. c

More particularlystated, I seek to use a diaphragm of moderate size in connection .10 with a sound reflector of suitable form, in such manner as to obtain substantially the same advantages as are ordinarily to be expected from the use of a diaphragm, alone, of larger size. 15. llnconnection with talking machines, loud speakers, broadcasting receivers and the like, it is common practice to use a diaphragm of small size, say from one and oneeighth inches to two inches in diameter, in connection with a horn having a'maximum cross diameter much greater than that of the diaphragm. Of recent years there has been a tendency to substitute, for the horn and small diaphragm, a hornless apparatus, consisting as far as practicable of a diaphragm of relatively large size. This ofiers advantages of simplicity, compactness and lightness, together with possibilities of cheapness. lln order to give adequate volume to the sounds produced, however, it is necessary to employ some expedient to'cause the entire diaphragm, or a large portion of it, to move as a unit in the production of sound waves. As a rule, it is desirable to either make the diaphragm stifl, or to maintain it under tension, or to brace it at a. plurality of points in order to insure that the diaphragm, when actuated, will as far as practicable execute piston-like movements againstthe air.

A. conical diaphragm, either stifi or under tension, is appropriate for the purpose just mentioned, but here arises a difliculty. If the conical diaphragm be too small, it does not make contact with a suiiiciently large area of the adjacent air, and if too large, it does not readily execute the required piston-like vibratory movements, and especially for the finer overtones. It is indeed a difficult matter to so proportion aparticular diaphragm as to give it an area large enough for adequate volume, and yet small enough for fidelity in the reproduction of the higher overtones, and of complex and delicate sounds. The usual expedient is a compromise, namely, the use of a conical diaphragm not less than nine inches and not more than fifteen inches in diameter.

I have made the discovery that by the use of a relatively small diaphragm of suitable form, say a conical diaphragm four, five or six inches in diameter and operated under tension or not as conditions ma' require, coupled with a reflecting sound 0 amber of special form and used as hereinafter described, I can give proper expression to a wide range of overtones, and produce sounds of great delicacy and complexity, and yet can produce adequate volume such as is not ordinarily produced except by a diaphragm of much larger size or by the addition of a horn.

Reference is made to the accompanying drawing forming a part of this specification,

and in which like reference characters indicate like parts throughout the several figures.

Figure 1 is a substantially central vertical section of an electrically operated loud speaker made in accordance with my invention.

Figure 2 is a front elevation oi the device appearing in Figure 1.

1 Figure 1, looking in the direction indicated by the arrows.

Figure a is a fragmentary central vertical section showing a form of my device difiering slightly from the one appearing in the other figures.

A sound reflector 5 has substantially a frusto conical form but is flared slightly outward at 6 as shown more particularly in Figure l, and is provided with a thick portion 7, having the form of a rather flat cone. Thus the sound reflector may be considered as having a bottom in the form of a cone, the apex of the cone extending out into the reflector.

'The sound reflector is provided with an annular. flange 8, extending inwardly. The sound reflector is provided with screws 9, by aid whereof it is held in position upon a wall 10 or analogous support. 7

A spider ring 11 is fitted upon the annular flange 8 and held in position by screws *12. The form of this spider is indicated more particularly in Figure 3. Arms 13, in this instance three in number, are integral with the spider ring 13 and extend radially inward therefrom. These arms are sepagure 3 is a section on the line 33 of rated by openings 1 and car y a beari 15 having the form of a neck, as shown in Figure 1.

Extending through the bearing 15 is an adjusting rod 16, carrying a knob 17 serving as a handle for enabling the rod to be moved back and forth in the direction of its length, or to be turned clockwise or counterclockwise, as the case may be. The bearing 15 carries a set screw 16, for locking the adjusting rod 16. A sound guiding member 18, having the general form of a conoid and is hollow, is provided adjacent its apex with a bearing 19, having the form of a neck, through which extends the adjusting rod 16. A. pin 20 holds the sound guiding member 18 firmly upon this adjusting rod.

Carried by the sound guiding member 18, and extending into the hollow thereof, is a spider 21, held in position by a clamping ring 22, and engaging this clamping ring is a conical diaphragm 24, held in position by a cap ring 23. The conical diaphragm 24 is of suitable form to mate the adjacent.

conical bottom 7 of the sound reflector 5.

Connected with the center of the diaphragm 24, and thus at the apex of the cone represented by the diaphragm, is a little rod 25, extending to a spring armature 26 and secured firmly thereto. Magnetic mechanism 27, carried by the spider 21, co-operates with the armature 26 and thus serves therewith as motor mechanism for 'actuating the diaphragm. designate the spider 21 and parts carried thereby as a cone unit, for actuating the diaphragm. Any other type of motor mechanism suitable for actuating a diaphragm may be substituted for this cone unit. o

It will be noted that between the conical diaphragm 24: and the adjacent surface of the cone 7 there is a space 28 of substantially conical form. This space can be varied by adjusting the position of the diaphragm 24 relatively to the cone 7 and this is accomplished by shifting the adjusting rod 16 slightly, in the direction of its length.

It will also be noted that when the adjusting rod 16 is drawn outwardly by the knob 17, or in other words is moved to the right according to Figure 1, there is a consequent enlargement of the annular'space immediately encircling the cap ring 23, due to the fact that this .cap ring is moved into a portion of a little larger diameter, of the sound reflector 5.

Thus it is apparent that the operator, by grasping the knob 17 and moving it to the right according to Figure 1, can vary the damping space 28 and canoregulate with considerable nicety the space encircling the cap ring 23. The operator can. also, by turning the knob 17, slightly rotate the diaphragm 24 relatively to the cone 7. Thus if some of the parts be Worn,mis-

For convenience 1 shapcn or badly fitted, it is possible to get a good adjustment of the diaphragm 24 relatively to the cone 7. This is important in instances where it is found from experi ence that the damping space 28 must be reduced to a minimum, and where it is diflicult to thus reduce the space without allowing the diaphragm to touch the cone 7, or in other words the bottom of the sound reflector.

I have made the discovery that with the apparatus constructed as above described and properly adjusted and the diaphragm actuated in the manner here contemplated, the diaphragm throws off sound waves which proceed at first backwardly and outwardly and then forwardly, so as to pass out of the apparatus at the right, according to Figure 1. It appears that the sound waves, formed initially by a large middle portion of the conical diaphragm, or in fact by piston-like movements of the diaphragm practically in its entirety, follow the adjacent surface of the cone 7, and as thus guided pass around the cap ring 23, into the space between the sound reflector 5 and sound guiding member 18, and that as the waves move to the right according to Figure 1 within this space, they develop and passout at the right in much the same manner that sound waves ordinarily develop and pass out of an ordinary horn. r

The net result is .that in my apparatus 1 claim all the advantages of a horn as used in connection with a relatively small diaphragm, and yet I get far greater,compactness and many other advantages, while avoiding the well known disadvantages peculiar to the use of a horn.

I find, moreover, that the volume of the sound produced by my apparatus is very great, so that I am enabled to reduce considerably the size of the diaphragm required to produce a: given volume. 1 find also that with a diaphragm thus reduced in size, the intonation is better and the fidelity. of vreproduction is greater than where a larger diaphragm is used, but without a horn or any equivalent of a' horn.

In the form of my device appearing in Figure 4n the sound guiding member 28, corresponding to the sound guiding member 18 above described with reference to the other figures, is provided withv openings 29. These openings are for two distinct purposes: First they serve as an egress for such sound waves as are thrown directly off from the adjacent face of the diaphragm and 2 thus are not reflected, and second they serve asa ventv for promoting freedom of movement of the diaphragm.

The operation of my device can be readily understood from the foregoing description.

actuated in any appropriate way, as by means of the motor 1nechanism described, sound waves are thrown off, andpass out of the apparatus.

In the forms shown in Figures 1 and 3, inclusive, the sound waves proceed from one side only of the diaphragm, but in the other form shown, shown in Figure 4, the sounds proceed from both sides of the diaphragm. In either case the operator makes a suitable adjustment to obtain the-best result, the adjustment being varied from time to time as required.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is as follows:

1. An acoustical mechanism comprising an acoustical member having substantially the form of a hollow cone frustum and provided with a closed end serving as a bot tom, said closed end having the'proximate form of a cone with its apex extendinginto said hollow conefrustnm, and a vibratory diaphragm located within said acoustical member and disposed adjacent said closed end in order to project sound waves thereagainst, said vibratory diaphragm having the proximate form of a hollow cone with its apex extending in the same direction as said first mentioned apex.

2. An apparatus of the character described, comprising a sound reflector in hollow form, a vibratory diaphragm located within said sound reflector and coacting therewith for the production of sound waves, a sound guiding member located within said sound reflector, and mechanism connected with said vibratory diaphragm and said sound guiding mechanism. for adjusting them relatively to said .sound reflector.

3. An apparatus of the character described, comprising a sound reflector in hollow form, a vibratory diaphragm and a sound guiding member connected together as a unit and located within said sound reflector and coactin therewith and mechanism connected wit said sound guiding mechanism and controllable by theoperator for adjusting the position of said vibratory diaphragm and said sound guiding member relatively to said sound reflector.

4.. An apparatus of the character 'described, comprising a sound reflector in hollow form, a vibratory diaphragm located within said sound reflector, sound guiding mechanism located within said sound reflector and coacting therewith order to develop sound waves produced by said diaphragm, and mechanism connected with said sound reflector and with said diaphragm and controllable by the operator for adjusting the position of said diaphragm with reference to said sound reflector.

5. An apparatus of the character described, comprising a sound reflector in hollow form, a vibratory diaphragm located within said sound reflector, sound guiding mechanism located within said sound reflector and coacting therewith in order to develop sound waves produced by said diaphragm, and mechanism connected with said sound reflector and with said sound guiding mechanism located therein, for adjusting the position of said sound guiding mechanism relatively to said sound reflector.

6. An acoustical mechanism comprising an acoustical member-having substantially the form of a hollow cone frustum, and-provided with a closed end serving as a bottom, a vibratory diaphragm located within said hollow cone frustum and disposed adjacent said closed end in order to project sound waves directly against said closed end, and a sound guiding member having the proximate form of a hollow cone, with its apex extending away from the closed end of said hollow cone frustum.

7. A device of the character described, comprising a hollow member fashioned into a sound reflector a sound guiding member located within SZJd l'lOllOW member and provided with a surface which diverges from the wall of said sound reflector, and a vibratory diaphragm disposed within said hollow member and located between said sound guiding member and an adjacent portion of said hollow member,\ for the purpose of throwing ofl sound waves into the space between said sound guiding member and the adjacent portion of said sound reflector.

8., An apparatus of the character described, comprising a sound reflector in hollow form, a vibratory diaphragm located within said sound reflector and positioned from the internal surface thereof by an unobstructed space in order to project sound waves directly against said internal surface, and a sound guiding member located within said sound reflector and coacting therewith for guiding said sound waves as reflected from said internal surface.

9. An acoustical mechanism comprising an acoustical hollow member provided with an end portion serving as a bottom, a vibratory diaphragm located within said hollow member and disposed adjacent said end.

portion so as to project sound waves directly against said end portion, and a sound guidingmember having the proximate form of a hollow cone, with its. apex extending away from said end portion of said hollow member. Y

10. A device of the character described comprising an acoustical hollow member provided with a portion serving as a bottom and having the proximate form of a cone, a vibratory diaphragm located within said hollow member and having the proximate form of a cone so located that its apex extends in the same direction as the apex of said first mentioned cone, said diaphragm being positioned from said portion of said 5 hollow member by an unobstructed space in order to project sound Waves directly against said portion, and mechanism conof Kings and State of New York, this 17th day of March, 1926.

MORRIS GRUBER, 

